Keen observation!
Yes indeed, the strangest possible thing happened, because God in Christ so predestinated it. ['Predestined' does not feel right for my old head.] And so was it for all who attended that wedding feast. It was completely against what they were used to.
The passover was "most solemnly observed feast" ALTHOUGH it was the, REDEMPTION-FEAST of Israel. But it had lost all that for the Jews. They were awful legalists and could not stand the Presence of Joy or its enjoyment with gladness and [perhaps even a little bit of mirth?].
Jesus' Presence brought the TRUE dimension of that feast day, "the third day of the FEAST"--remember--to the fore again--revived it as it were from its grim grave: "First Sheaf Waved Before the LORD" of the passover-SUFFERING of Yahweh's "third day".
So, no, precisely FOR the objections <<it sure seems like an awfully big reach. It says it was a wedding, not the Passover. If it were the Passover, wouldn't they say so? Especially if it were significant?>>, it was the passover because “Christ our Passover” was there, and 'raised a fore-toast' to his Resurrection from the dead which the passover of the exodus, already, and now this "third day of the feast" again, fore-shadowed.